Little Help with Sharp LC-80LE642U

[Robottom]

I have a Sharp 80" TV that started giving me an error code, 1 short, 1 long blink.
I read that is a "Lamp / Inverter" error and am trying to figure out if there is a problem with one of the boards or with the LEDs.

I noticed that there was some light coming from the backlight section for a brief period after plugging the TV in while holding "Input" and "Vol -" at the same time. That only stayed on for a few seconds then shut off. It was enough time to put a meter on the leads from the power board (RUNTKB096WJQZ) L1 pin 1, 3 and 5 tested to chasse ground ~130 VDC. Each LED strip is 30 LEDs long and there are 15 strips on the backlight section.

I saw several videos and blogs where stacking up a bunch of 9V batteries would work to test the LED strips. So I separated the backlight section from the LCD panel to test the LED backlights. I tried 10 batteries = 90 VDC first but got nothing, then bumped up to 12 batteries 108 VDC (the batteries are brand new so it tests with a meter at 132 VDC).

Anyway, according to what I've seen and read, this should be enough voltage to power one complete LED strip, but am getting nothing, no light at all.

I am sure that the voltage is actually making it onto the strip because I tied the battery stack leads to the connector pins and tested across the little copper tabs on the strip.

Before jumping to the conclusion that strip is bad, I tried another strip, same result, nada. So I am guessing that I'm doing something wrong.

Any help would be appreciated, thanks, best regards,
Tom

[Andrew F. Ali]

Re: Little Help with Sharp LC-80LE642U

You may have the voltage (V) but not the current (I) to sustain the for the backlight strip to turn ON....From what you explained....That points to a Backlight failure.......However before assuming that you should do a self-test on the PSU.

[dskall]

Re: Little Help with Sharp LC-80LE642U

Need good clear straight on pictures of back of tv with cover off and each board.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I don't have one shot that shows the whole back of the TV but I do have individual shots of the boards. The LC-80LE642U layout looks very much like any of the other 70", 80" or 90" models. 3 boards showing main to the right, tcon middle bottom and power to the left looking from the back.

Also, must report that I added 2 more 9V batteries to my stack and that was barely enough to light the LED strips. They all did come on, some just barely but I think a good indication that there are none shorted and none open.

Please see attached pics of boards and backlight section.

Is it safe to say that my backlight LEDs are OK even though some barely lit with the stack of 14 9V batteries?

What would be the next test, power board, main or tcon, and how should I go about that. I can reassemble the backlight section with the LCD panel and mount boards within an hour or two.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

First pic from the left is the main board, DKEYMF953FM06
Second pic from the left is the TCON board, DUNTKF975FM18
Third pic from the left is the power board, RUNTKB096WJQZ
Fourth, fifth and sixth pics are the backlight section and connectors.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I did find this in the manual showing the board layout and connections looking from the back.

[dskall]

Re: Little Help with Sharp LC-80LE642U

I don't know if that is a conclusive test as you are only running minimum current through them. Not enough to get them hot and thermally short or open. With the panel off I would connect all boards minus panel and power it on and see if all light up.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I don't know if that is a conclusive test as you are only running minimum current through them. Not enough to get them hot and thermally short or open. With the panel off I would connect all boards minus panel and power it on and see if all light up.

Same as before, lights up for a few seconds after plugging in while holding "Input" and "Vol -". The LEDs are pretty bright but I don't think they're staying on long enough to cause significant thermal change.

The symptoms have been identical since this first happened. As long as it's plugged in, blinking one short / one long. Unplug, hold "Input" and "Vol -", plug back in. LEDs light up for a few seconds then the power board clicks, and it goes right back into blink mode. Nothing visible has appeared on the screen even when the LEDs are on.

Is there a way to fool my power board into thinking that the LEDs are OK? I found this video that showed how to force the power supply to stay on so that I can see it is powering the backlight LEDs. Here -> (https://www.youtube.com/watch?v=fBWX34wTULw) this guy disconnects the cable from the main board and used jumpers and switches to simulate the inputs from the main board to fool the power board.

Unfortunately I do not have the same power board and the pins he was jumping are not all available on my board. I have RUNTKB096WJQZ which does not have any pin marked PWM1.

I'm thinking that might help decide if the issue is the power board or main board. I haven't ruled out the TCon but think that seems unlikely.

[dskall]

Re: Little Help with Sharp LC-80LE642U

You have panel off. You should be able to see if any are not lighting

[Robottom]

Re: Little Help with Sharp LC-80LE642U

Here's my test setup, basically the whole TV is together. I have the LCD laying face down on a bed with the backlight section on top, and connected, but propped open at the top. I'm keeping it open using the plastic pieces from where the stand goes in. The bezel is just laying on top so that I can use the buttons.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I took a video of exactly what's happening, but first some screen shots to show that all of the LEDs are coming on. The reason they don't look as bright in some shots as others is due to my inability to get exactly the right frame of the video to stop when I want to take a snap shot. Believe me, if the video loads, you'll see how bright they actually get.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

Website won't let me upload a video, invalid file.

What is happening exactly is that I have my wife hold the "Input" and "V0l -" buttons down and switch on the power. The system takes a second or so, then flashes the LEDs full strength, then after a few seconds, the power board clicks and the icon goes back to blinking.

The LEDs flash very briefly, maybe not even a whole second.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I also have to say that it seems like the LEDs stayed on until the power board clicked when I tried this before but working from memory at this age isn't my strong suit any more. :-)

[dskall]

Re: Little Help with Sharp LC-80LE642U

The first picture right side looks like a couple not lighting. The shear number of leds makes it hard to detect.

[budwich]

Re: Little Help with Sharp LC-80LE642U

I think what you are seeing in the first picture isn't that the led isn't lighting, its being blocked in the picture by the "standoff pin".

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I'm almost positive all the LEDs were all lighting. We repeated the reset procedure several times. Also, I'm hearing that they should have stayed on until the power board clicked, as I described earlier, they should not have just flashed.

If bad LEDs were the cause wouldn't the ones that were still ok stay on until the power board clicked and shut off? Shouldn't I have been able to see clearly for at least a few seconds that some were on and others were not?

The change from earlier, staying on until the power board clicks, verses big flash makes me think the power board was headed south the first few tries and is completely shot now. That's not to say that some of the LEDs aren't bad too but honestly, think they're OK.

[martino]

Re: Little Help with Sharp LC-80LE642U

Following this. Can you tell me how you took the lcd panel off safely? That's a big panel

[Robottom]

Re: Little Help with Sharp LC-80LE642U

Following this. Can you tell me how you took the lcd panel off safely? That's a big panel

I laid the TV face down on a bed and pulled the back off.
Disconnected at the board end speakers etc. anything attached to the bezel.
Then very carefully stood it up on the top edge.
And walk it on edge across the bed to make room to lay it down on it's back.
Be careful not to let the bezel catch on the covers or it will get pulled off.
If you keep it a little at an angle leaning / favoring the back it's not too hard.

Anyway, with the TV on it's back, and bezel mounted equipment cables disconnected, the bezel lifts right off just pull the tabs.
Now undo the screws holding the backlight and LCD frames together.
However, not all of the screws. Take all of the screws out of the sides but not the top and bottom. I left every other screw in top and bottom.

Then go through the same lift and walk on edge procedure to get it laid back face down.

Slide enough of the screen over the edge of the bed to remove the screws from the top or bottom, and slide and repeat for the other end.

Once all the screws are out, you can lift the backlight section off of the LCD panel without too much trouble, IT TAKES TWO PEOPLE. Fortunately, my wife was home to help. She's a sturdy girl :-)

I actually found it more convenient to just leave the backlight section on top, just propped open to see what the LEDs were doing.

[budwich]

Re: Little Help with Sharp LC-80LE642U

I'm almost positive all the LEDs were all lighting. We repeated the reset procedure several times. Also, I'm hearing that they should have stayed on until the power board clicked, as I described earlier, they should not have just flashed.

If bad LEDs were the cause wouldn't the ones that were still ok stay on until the power board clicked and shut off? Shouldn't I have been able to see clearly for at least a few seconds that some were on and others were not?

The change from earlier, staying on until the power board clicks, verses big flash makes me think the power board was headed south the first few tries and is completely shot now. That's not to say that some of the LEDs aren't bad too but honestly, think they're OK.

I think the LED's are "current driven" and thus system monitors the current going "out". It shuts the system down if that monitor determines that the current is heading out of range.

Not an expert, but from my reads here and there, is that the error codes aren't always "absolute" in that the software related to this function isn't always "exact". Have you tried any other tests beside the "force on" with the buttons and power? ie. disconnecting cables at various points from the tcon to the panel, corner cables on the panel, etc.... to see if perhaps there is something else happening that the "flash code" is "hiding".

Of course, if all your leds are indeed good, then the next bet would be the power supply / inverter.... maybe.

[Robottom]

Re: Little Help with Sharp LC-80LE642U

I think the LED's are "current driven" and thus system monitors the current going "out". It shuts the system down if that monitor determines that the current is heading out of range.

Not an expert, but from my reads here and there, is that the error codes aren't always "absolute" in that the software related to this function isn't always "exact". Have you tried any other tests beside the "force on" with the buttons and power? ie. disconnecting cables at various points from the tcon to the panel, corner cables on the panel, etc.... to see if perhaps there is something else happening that the "flash code" is "hiding".

Of course, if all your leds are indeed good, then the next bet would be the power supply / inverter.... maybe.

I tried disconnecting the main board from the power board but that also removes the reset or start signal and it never turns the LEDs on at all.

I also tried removing the LED + and - cables. With both cables removed, I see a 200V spike, then drops off to about 150V. With both LED cables connected, I see a spike of about 140V but then drops off pretty quickly to somewhere below 120. I'm guessing that the power board can't handle the load, LEDs dim or go out all together which eventually (within a second or so) leads to a lamp failure signal from the main board.

I'm going to order the power board for sure, at least if the new one shows up and I'm back to having the LEDs stay on for a few seconds I'll have another chance to be 100% certain that they're all on or not.